Apparatus and method for preparing paving mixtures

ABSTRACT

A paving mixture apparatus broadly comprising a conveyance zone, a vertical transition zone, a spray bar, a filler material feeder, and an agitation zone. The spray bar is configured to deliver a substantially continuous and laminar sheet of liquid mixture in the vertical transition zone. The substantially continuous and laminar sheet of liquid mixture urges aggregate from the conveyance zone and filler material from the filler material feeder downward in the vertical transition zone toward the agitation zone and reduces static electricity buildup in the filler material.

RELATED APPLICATIONS

The present application claims the priority benefit of U.S. Provisional Patent Application Ser. No. 61/754,941 entitled “METHOD AND APPARATUS FOR PREPARING PAVING MIXTURES,” filed Jan. 21, 2013, the entirety of which is incorporated herein by reference.

BACKGROUND

The present invention is broadly concerned with paving mixture apparatuses for use in a road or a surface paver. More particularly, embodiments of the present invention relate to improved paving mixture apparatuses configured to more efficiently prepare an improved paving mixture.

Pavers are often used for preparing a paving mixture and for applying the paving mixture to a surface such as a road or a parking lot. Pavers include a conventional paving mixture apparatus which comprises an aggregate conveyor, a filler feeder, a transition zone for channeling ingredients of the paving mixture into an agitator, and one or more injectors for injecting water and an emulsion into the paving mixture. Conventional paving mixture apparatuses prepare a paving mixture that may include an aggregate, a filler material (e.g., fiber segments), water, a liquid additive, and an emulsion. The aggregate and the filler material are conveyed or fed into the transition zone in which or after which water, emulsion, and additive are added from the injectors.

Conventional paving mixture apparatuses are deficient, however, in a number of ways. For example, static electricity often builds up in the filler material as it is fed into the transition zone, which results in the uneven distribution of filler material. Also, the filler material often does not flow properly through the transition zone, resulting in the filler material clogging up the transition zone or resulting in loss of the filler material out through the aggregate inlet and/or build-up of the fiber material in the aggregate feeder. Moreover, the water, emulsion, and additive often do not mix homogenously into the paving mixture.

Accordingly, there is an unresolved need in the art for improved paving mixture apparatuses.

SUMMARY

Embodiments of the present invention solve the above-described problems by providing an improved apparatus for preparing paving mixtures.

The improved paving mixture apparatus broadly comprises a conveyance zone, a vertical transition zone, a spray bar, a filler material feeder, and an agitation zone.

The conveyance zone includes an aggregate conveyor or chute leading to the vertical transition zone.

The vertical transition zone is adjacent to the conveyance zone and includes a vertical transition zone inlet on one side of the vertical transition zone, a filler material inlet on an opposite side of the vertical transition zone, and a vertical transition zone outlet at a lower end of the vertical transition zone leading to the agitation zone.

The spray bar is disposed in or near the vertical transition zone and includes a set of dividers that may include a water inlet, water distribution channels, spacers, flow restrictors, an additive mixer, and a wide downward facing outlet.

The filler material feeder is adjacent to the vertical transition zone opposite the conveyance zone.

The agitation zone is located below the vertical transition zone.

To prepare the paving mixture, the conveyor delivers aggregate into the vertical transition zone through the vertical transition zone inlet and the filler material feeder delivers filler material into the vertical transition zone through the filler material inlet. The spray bar directs a continuous downward-flowing laminar sheet of liquid mixture between the aggregate and the filler material as they enter the vertical transition zone. The sheet of liquid then contacts the aggregate and the filler material, which evenly wets the filler material and urges the aggregate and the filler material downward toward the agitation zone for further mixing.

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Other aspects and advantages of the present invention will be apparent from the following detailed description of the embodiments and the accompanying drawing figures.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

Embodiments of the present invention are described in detail below with reference to the attached drawing figures, wherein:

FIG. 1 is an elevation view of a paver including a paving mixture apparatus constructed in accordance with an embodiment of the present invention;

FIG. 2 is an enlarged elevation view of the paving mixture apparatus of FIG. 1;

FIG. 3 is a bottom perspective view of a spray bar of the paving mixture apparatus of FIG. 1;

FIG. 4 is a top perspective view of the spray bar of FIG. 3;

FIG. 5 is an exploded view of the spray bar of FIG. 3; and

FIG. 6 is a sectional view of the spray bar of FIG. 3.

The drawing figures do not limit the present invention to the specific embodiments disclosed and described herein. The drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following detailed description of the invention references the accompanying drawings that illustrate specific embodiments in which the invention can be practiced. The embodiments are intended to describe aspects of the invention in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments can be utilized and changes can be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense. The scope of the present invention is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled.

In this description, references to “one embodiment”, “an embodiment”, or “embodiments” mean that the feature or features being referred to are included in at least one embodiment of the technology. Separate references to “one embodiment”, “an embodiment”, or “embodiments” in this description do not necessarily refer to the same embodiment and are also not mutually exclusive unless so stated and/or except as will be readily apparent to those skilled in the art from the description. For example, a feature, structure, act, etc. described in one embodiment may also be included in other embodiments, but is not necessarily included. Thus, the present technology can include a variety of combinations and/or integrations of the embodiments described herein.

Turning now to the drawing figures, and particularly FIGS. 1 and 2, a paving mixture apparatus 10 for use on a paver 100 for paving a surface 102 and constructed in accordance with an embodiment of the invention is illustrated. The paving mixture apparatus 10 broadly includes a conveyance zone 12, a substantially vertical transition zone 14, a spray bar 16, a filler material feeder 18, and an agitation zone 20.

The conveyance zone 12 is positioned near a top of the vertical transition zone 14 and includes a conveyor 22 such as a conveyor belt, an auger, or a chute disposed therein. The conveyance zone 12 is configured to deliver aggregate and a mineral filler such as cement (distinguished from the filler material fed from the filler material feeder 18) to the vertical transition zone 14.

The vertical transition zone 14 is provided for channeling mixing ingredients into the agitation zone 20 and is generally defined within a spray hood 24 and positioned at a distal end of the conveyance zone 12. The spray hood 24 defines a vertical transition zone inlet 26 and a filler material inlet 28 near opposite upper sides of the vertical transition zone 14 (so as to be horizontally positioned on opposite sides of a liquid mixture delivered from the spray bar 16, for example) and a vertical transition zone outlet 30 near the bottom of the vertical transition zone 14. The vertical transition zone inlet 26 and the filler material inlet 28 are vertically positioned above the transition zone outlet 30 and below the discharge outlet of the spray bar 16, described below.

Turning now to FIGS. 2-6, the spray bar 16 is provided for delivering water into the vertical transition zone 14 between the vertical transition zone inlet 26 and the filler material inlet 28. The spray bar 16 is disposed in or near a top of the vertical transition zone 14 (FIG. 2) and includes a water inlet plate 32, a water inlet spacer plate 34, a flow limiter plate 36, a limiter spacer plate 38, a water profile plate 40, a water outlet spacer plate 42, and an additive mixer mounting plate 44, as best shown in FIGS. 5 and 6.

The water inlet plate 32 is provided for receiving a flow of water therein and defines a water inlet 46 such as a hole or a slot. The water inlet plate 32 is connected to a water injector 48 such as a flanged water pipe or tube at the water inlet 46.

The water inlet spacer plate 34 is provided for spreading the water flow horizontally within the spray bar 16. The water inlet spacer plate 34 is adjacent the water inlet plate 32 and defines a flow distribution chamber 50, which may have a width-to-height ratio of no less than 3:1, 5:1, 10:1, or 20:1 and may be approximately 10inches to approximately 30 inches wide and approximately 1 inch to approximately 3 inches tall.

The flow limiter plate 36 is provided for smoothing out the water flow and is adjacent the water inlet spacer plate 34. The flow limiter plate 36 defines a set of flow restriction openings 52, which may be approximately ⅛^(th) of an inch in diameter to approximately 0.5 inches in diameter and may be arranged in rows, columns, and/or groupings of between 10 to 50 openings each.

The limiter spacer plate 38 is provided for further smoothing out the water flow and is adjacent the flow limiter plate 36. The limiter spacer plate 38 defines between 1 to 10 flow transition chambers 54 and complete or partial dividers 56 spaced therebetween. The limiter spacer plate 38 also defines one or more drainage passages 57 near a lower portion of the flow transition chambers 54 of the limiter spacer plate 38.

The water profile plate 40 is provided for shaping the water flow as described in detail below and is adjacent the limiter spacer plate 38. The water profile plate 40 defines between 1 to 10 flow profile openings 58, which may be thin slots each having a width-to-height ratio of no less than 3:1, 5:1, 10:1, 20:1, or 40:1. The water profile plate 40 also defines one or more openings connecting the drainage passages 57 of the limiter spacer plate 38 to a flow chamber of the water outlet spacer plate 42 therethrough.

The water outlet spacer plate 42 is provided for further shaping the water flow as described below and is adjacent the water profile plate 40. The water outlet spacer plate 42 defines a flow chamber 60 with an elongated discharge outlet 62 (FIG. 6) having no more than 10, 6, 4, 2, or 1 elongated openings having a width-to-thickness ratio of at least 5:1, 10:1, 20:1, 30:1, 40:1, or 50:1 for delivering the water flow substantially downward (dashed arrows in FIG. 3) into the vertical transition zone 14. The thickness of the water outlet spacer plate 42 (and hence the flow chamber 60 and the elongated discharge outlet 62) may be chosen to generate an appropriate water flow. Alternatively, the outlet spacer plate 42 may be combined with the water profile plate 40 into a single plate.

The additive mixer mounting plate 44 is provided for partially enclosing the flow chamber 60 of the water outlet spacer plate 42 and for mounting an additive mixer 66 thereon. The additive mixer mounting plate 44 is adjacent to the water outlet spacer plate 42 and defines a secondary water outlet 64 that may be no more than 0.25 inches to 1.5 inches in diameter. The additive mixer 66 is mounted on the additive mixer mounting plate 44 at the secondary water outlet 64 for receiving water from the flow chamber 60 of the water outlet spacer plate 42 therethrough and for mixing a liquid additive with the water from the secondary water outlet 64 to form a liquid mixture. The additive mixer 66 includes a lower opening for delivering the liquid mixture substantially downward (central dashed arrow in FIG. 3) into the vertical transition zone 14.

It will be understood that the widths, heights, and thicknesses of the above plates 32-44 and the order and arrangement in which the above plates 32-44, the water injector 46, and the additive mixer 66 are assembled may be chosen to achieve a desired water flow and liquid mixture.

A plurality of fasteners 68 may be provided for securing the above plates 32-44, the water injector 48, and the additive mixer 66 together. The fasteners 68 may include bolts and nuts, pins, rivets, clamps, or other type of fastener and may be inserted through a set of holes 70 spaced around the perimeters of the above plates and aligned with each other.

Turning again to FIG. 2, the filler material feeder 18 is provided for delivering a filler material such as glass fibers or other fibers to the vertical transition zone 14 and is positioned near a top of the vertical transition zone 14 opposite the conveyance zone 12. The filler material feeder 18 may include a filler cutter 72 having a cutting wheel 74 configured to cut the filler material into small strands approximately ¼^(th) of an inch to approximately ¾^(th) of an inch long and a filler chute 76 connected to the spray hood 24 at the filler material inlet 28. The filler material inlet 28 and the filler chute 76 guide the filler material into the vertical transition zone 14 towards the sheet of liquid mixture.

The agitation zone 20 is provided for mixing the ingredients and is positioned below the vertical transition zone 14 and defined within an agitator 78 such as a conventional pug mill having several paddles or corkscrew protrusions extending radially from one or more rotating shafts in the agitation zone 20. The agitator 78 may also define an emulsion inlet 80 positioned near a top of the agitation zone 20 wherein an emulsion injector 82 is attached to the agitator 78 at the emulsion inlet 80. The agitation zone 20 leads to a spreader box 84 or other application section of the paver 100 configured to receive the mixed ingredients from the agitation zone 20 and to apply the paving mixture to the surface 102 to be paved.

Preparing a paving mixture (e.g., a slurry or a micro surfacing mixture) using the above-described paving mixture apparatus 10 is now described. The aggregate is delivered by the conveyor 22 in the conveyance zone 12 to the vertical transition zone 14 through the vertical transition zone inlet 26. Optionally a mineral filler such as cement may be added to the aggregate in the conveyance zone 12.

The filler material is delivered to the cutting wheel 74 by the filler material feeder where it is cut by the cutting wheel 74 into small strands as described above. The filler material is then delivered into the vertical transition zone 14 at the filler material inlet 28 via the filler chute 76. Alternatively, the filler material may be delivered into the vertical transition zone 14 pneumatically or via any other suitable means.

A substantially continuous sheet of water or liquid mixture is delivered to the vertical transition zone 14 from the elongated discharge outlet 62 of the spray bar 16 and the lower opening of the additive mixer 66 as the aggregate and the filler material are being delivered to the vertical transition zone 14 from the conveyance zone 12 and the filler material feeder 18, respectively. To create the liquid mixture, a supply of substantially turbulent water is delivered to the spray bar 16 by the water injector 48 through the water inlet 46 and a supply of additive is delivered to the additive mixer 66. The water flows through the flow distribution chamber 50 of the water inlet spacer plate 34 in which the water is spread horizontally. The water then flows through the flow restriction openings 52 of the flow limiter plate 36 in which the turbulence of the water begins to be reduced. The water continues to flow through the flow transition chambers 54 of the limiter spacer plate 38 in which the water transitions to a substantially laminar flow. The water then flows through the flow profile openings 58 of the water profile plate 40 in which the water begins to form a wide sheet. The water then flows into the flow chamber 60 of the water outlet spacer plate 42 and continues to develop into a wide sheet of water, which exits downward (laterally spaced dashed arrows in FIG. 3) into the vertical transition zone 14 through the elongated discharge outlet 62 as a substantially continuous wide sheet having generally the same width-to-thickness characteristics of the openings of the discharge outlet 62 described above and may extend substantially the width of the vertical transition zone 14. The continuous sheet of water may be directed downward or at an angle of no more than 60, 45, 30, 20, 15, 10, or 5 degrees from vertical and may be directed toward the vertical transition zone inlet 26 or toward the filler material inlet 28. Concurrently, some of the water in the outlet spacer plate 42 flows through the secondary water outlet 64 and is mixed with additive in the additive mixer 66 to form a liquid mixture. The liquid mixture from the additive mixer 66 is directed generally downward (middle dashed arrow in FIG. 3) and may be angled toward the continuous sheet of water to mix with the continuous sheet of water, thus forming a continuous sheet of liquid mixture, as best shown in FIG. 2.

The continuous sheet of liquid mixture contacts the aggregate and/or the filler material in the vertical transition zone 14, which evenly wets the aggregate and/or the filler material and urges the aggregate and the filler material downward towards the vertical transition zone outlet 30.

The above-described aggregate, cement, liquid mixture, and filler material fall downward by gravitational force (and optionally by some kinetic energy imparted on them by the above-described components) into the agitator 78 through the vertical transition zone outlet 30. These ingredients are then physically mixed together in the agitation zone 20 by the agitator 78. Additionally, an asphalt-containing emulsion is added to the paving mixture by the emulsion injector 82 through the emulsion inlet 80. The paving mixture is then applied to the road, parking lot, or other surface 102 via the spreader box 84 or other application section of the paver 100.

The above-described paving mixture apparatus 10 provides several advantages over conventional paving mixture apparatuses. For example, the paving mixture apparatus 10 creates a more consistent paving mixture. Also, the paving mixture apparatus 10 more efficiently combines the aggregate and the filler material. Moreover, the paving mixture apparatus 10 also allows an operator to more easily control the mixing ratios and properties of the paving mixture.

Specifically, as shown in FIG. 2, the spray bar 16 evenly coats the aggregate and/or the filler material with the continuous sheet of water or liquid mixture in the vertical transition zone 14 of the paving mixture apparatus 10. This results in a more consistent paving mixture and a higher quality surfacing. In addition, premixing the water and the additive together before introducing them to the aggregate and the filler material provides improved dispersion of the additive in the paving mixture.

The continuous sheet of water or liquid mixture also more efficiently and more evenly combines the aggregate and the filler material by urging the aggregate and/or the filler material downward towards the vertical transition zone outlet 30 when they enter the vertical transition zone 14. This helps prevent the aggregate and/or the filler material from clogging or reversing flow (e.g., exiting the vertical transition zone 14 backwards through the vertical transition zone inlet 26 and the filler material inlet 28 or exiting the agitator 78 upwards through the vertical transition zone outlet 30), which reduces the amount of maintenance required. The continuous sheet of water or liquid mixture also reduces the amount of filler dust released into the air and reduces static electricity buildup in the filler material, which prevents the filler material from unevenly conglomerating together or clinging to the aggregate.

Moreover, the mixing ratios and other properties of the paving mixture may be controlled. For example, the mixture ratio of water to additive in the liquid mixture (and hence the paving mixture) may be accurately adjusted by changing the water flow through the elongated discharge outlet 62 and the secondary water outlet 64 of the spray bar 16 and the additive flow rate in the additive mixer 66. In addition, the wetness of the filler material or the aggregate may be altered by adjusting the angle and the flow rate of the continuous sheet of water or liquid mixture of the spray bar 16 as it enters the vertical transition zone 14. For example, the discharge openings 62 of the water outlet spacer plate 42 of the spray bar 16 may be positioned near and angled towards the filler material inlet 28 for more directly wetting the filler material or may be positioned near and angled towards the vertical transition zone inlet 26 for more directly wetting the aggregate entering the vertical transition zone 14.

Although the invention has been described with reference to the embodiments illustrated in the attached drawing figures, it is noted that equivalents may be employed and substitutions made herein without departing from the scope of the invention as recited in the claims. 

Having thus described various embodiments of the invention, what is claimed as new and desired to be protected by Letters Patent includes the following:
 1. A paving mixture apparatus for preparing a paving mixture to be applied to a surface, said paving mixture comprising aggregate, water, and an asphalt-containing emulsion, said paving mixture apparatus comprising: a conveyance zone for transporting aggregate; a vertical transition zone defining a transition zone inlet for receiving aggregate from said conveyance zone and a transition zone outlet positioned at a lower elevation than said transition zone inlet; a spray bar configured to deliver water into said vertical transition zone, said spray bar defining at least one elongated discharge outlet for discharging a substantially continuous sheet of water in said transition zone; and an agitation zone for mixing an asphalt-containing emulsion with water and aggregate received from the vertical transition zone.
 2. The paving mixture apparatus of claim 1, further comprising a filler material feeder for supplying fiber segments to said transition zone, wherein said transition zone defines a filler material inlet for receiving said filler material segments from said filler material feeder.
 3. The paving mixture apparatus of claim 2, wherein said filler material inlet and said vertical transition zone inlet are horizontally positioned on generally opposite sides of said sheet of water.
 4. The paving mixture apparatus of claim 2, wherein said filler material inlet is configured to direct said filler material segments towards said sheet of water.
 5. The paving mixture apparatus of claim 4, wherein said filler material inlet is vertically positioned above said transition zone outlet and below said discharge outlet of said spray bar.
 6. The paving mixture apparatus of claim 1, wherein said discharge outlet comprises a single discharge opening having a length-to-thickness ratio of at least 20:1.
 7. The paving mixture apparatus of claim 1, wherein said discharge outlet faces generally downward.
 8. The paving mixture apparatus of claim 7, wherein said discharge outlet faces in a direction that is angled from vertical by at least 10 degrees and not more than 45 degrees.
 9. The paving mixture apparatus of claim 1, wherein said discharge outlet of said spray bar is vertically positioned closer to said transition zone inlet than to said transition zone outlet.
 10. The paving mixture apparatus of claim 1, wherein said spray bar defines a water inlet for receiving said water and includes an additive mixer operable to combine at least some of said water and said additive for forming a liquid mixture.
 11. The paving mixture apparatus of claim 1, wherein said agitation zone comprises an emulsion inlet for supplying said asphalt-containing emulsion to said agitation zone.
 12. The paving mixture apparatus of claim 1, further comprising a spreader box for receiving said paving mixture from said agitation zone and for applying said paving mixture to said surface.
 13. A spray bar for use in a paving mixture apparatus, the spray bar comprising: a water inlet plate defining a water inlet for receiving water therethrough; a water inlet spacer plate defining a flow distribution chamber for horizontally distributing the water; a flow limiter plate defining a plurality of flow restriction openings for reducing turbulence in the water; a limiter spacer plate defining at least one flow transition chamber for changing the water flow to a substantially laminar water flow; a water profile plate defining at least one flow profile opening having a width-to-height ratio of no less than 3:1; a water outlet spacer plate defining a flow chamber and having a discharge outlet defining a discharge opening having a width-to-thickness ratio of at least 5:1, the flow chamber being configured to develop a substantially continuous sheet of water; an additive mixer mounting plate defining a secondary water outlet for delivering water therethrough; and an additive mixer configured to mix additive with the water from the secondary water outlet of the additive mixer mounting plate for forming a liquid mixture.
 14. The spray bar of claim 13, wherein the water inlet plate and the additive mixer mounting plate are positioned on opposite sides of the spray bar.
 15. The spray bar of claim 13, wherein the limiter spacer plate is positioned between the flow limiter plate and the water profile plate.
 16. The spray bar of claim 13, wherein the water inlet spacer plate is adjacent the water inlet plate, the flow limiter plate is adjacent the water inlet spacer plate, the limiter spacer plate is adjacent the flow limiter plate, the water profile plate is adjacent the limiter spacer plate, the water outlet spacer plate is adjacent the water profile plate, and the additive mixer mounting plate is adjacent the water outlet spacer plate.
 17. A method of preparing a paving mixture, said method comprising: (a) introducing an aggregate into a vertical transition zone; (b) introducing a water-containing liquid into said vertical transition zone in the form of a substantially continuous liquid sheet having a width-to-thickness ratio of at least 5:1; (c) allowing said aggregate and said water-containing liquid to pass downwardly through said vertical transition zone and into an agitation zone; and (d) mixing said water-containing liquid, said aggregate, and an asphalt-containing emulsion in said agitation zone.
 18. The method of claim 17, wherein said liquid sheet has a width-to-thickness ratio of at least 20:1.
 19. The method of claim 17, further comprising introducing fiber segments into said vertical transition zone.
 20. The method of claim 17, wherein said aggregate is introduced into said vertical transition zone on one side of said liquid sheet and said fiber segments are introduced into said vertical transition zone on an opposite side of said liquid sheet.
 21. The method of claim 17, further comprising contacting a substantial portion of said fiber segments with said liquid sheet.
 22. The method of claim 21, wherein a substantial portion of said fiber segments become mixed with said water-containing liquid in said vertical transition zone.
 23. The method of claim 17, wherein said water-containing liquid comprises water and an additive.
 24. The method of claim 23, wherein said additive is mixed with said water below said spray bar. 